The telephone is in common use by people every day. The mouthpiece of the telephone handset frequently comes into contact with a user's mouth during use, resulting in the spread of infectious bacteria and viruses. Because these bacteria and viruses may remain on the mouthpiece for some time, diseases can be spread quickly to many people. To reduce the possibility of spreading these diseases, telephone sterilizers have been developed. These telephones use ultraviolet (UV) light as the sterilizing medium. Examples of these devices are found in U.S. Pat. Nos. 2,952,749, to Cobb et al.; 3,040,138, to Cobb; 4,486,628, to Thompson; and 5,008,933, to Kao et al. U.S. Pat. No. 2,952,749, disclosed a basic phone sterilizer system. A UV bulb is shown placed in the base unit of a phone. The system is operated by a simple switch connected to the cradle buttons on the phone. A timer can also be used to control the operation of the UV bulb. There is apparently no safety switch installed and anyone depressing the cradle buttons causes the light to energize. The 3,040,138 patent discloses placing the UV bulb in a carrier attached to the phone base. The removable cover gives ready access to the UV bulb for maintenance. This design uses a micro switch plus a thermal relay to operate the device. Again, apparently no safety devices are employed in this design. U.S. Pat. No. 4,486,628 uses a different system to sterilize the mouthpiece. Here, a radiation producing element is installed within the mouthpiece. This element produces electromagnetic radiation that is sufficient to sterilize telephone components. This radiation may be UV, but is not required to be UV. Unlike the previous designs, the radiation generator is located in the mouthpiece, not in the base unit. The system operates using a standard switch mounted in the cradle that operates when file receiver is placed in the cradle. Finally, U.S. Pat. No. 5,008,933 teaches using an IC timing control circuit to turn off the UV light source. This design also includes a safety switch, mounted independently from the cradle switch, to operate the UV bulb. Here, the user can operate the cradle switch to disconnect the line without causing the UV source to become energized.
Several problems are noted with file above described devices. Most of these devices have mechanical switches to activate the UV light. These switches can be activated while the receiver is off hook, thereby exposing the user to the UV light. Even the Kao et al. patent, that features a safety switch can cause problems because the one safety switch is located adjacent to the cradle switch. Such proximity can result in causing the UV bulb to become energized. Because exposing the eyes to direct UV light can be harmful, such systems are dangerous. Small children are especially curious and may inadvertently or even deliberately cause the UV light to come on, creating a hazardous situation.
Moreover, some of the above systems do not create a leak-proof fit between the mouthpiece and the cradle, thereby allowing UV light rays to escape from the phone. Finally, the designs of some of the above mentioned systems do not fully sterilize the telephone mouthpiece, thereby reducing the effectiveness of the system and increasing the possibility of the spread of disease.